It comes after officials in Rome found evidence that Zika could survive in sperm for as long as six months, based on the case of an Italian man who was infected with the disease while in Haiti.

The delay is intended to reduce the likelihood of a woman being exposed to Zika around the time of conception.

The CDC said: "Based on new though limited data, CDC now recommends that all men with possible Zika virus exposure who are considering attempting conception with their partner, regardless of symptom status, wait to conceive until at least six months after symptom onset or last possible Zika virus exposure."

Before, the CDC advised men with possible but unconfirmed Zika exposure - and no symptoms of the virus - to wait eight weeks from the last possible exposure before having unprotected sex.